Trojan.Narat

Hi,

recently, everytime I open an internet webpages, Norton Realtime scan notifiy me it found a Trojan.Narat virus; file name: c:\WINNT\msnarrtor.exe; I deleted the file, modify the register, and reboot the computer. but, norton still tell me found Trojan.Narat Virus verytime i open any webages.